How can peer-group analysis improve access certification?

Why This Matters for Security Teams

Peer-group analysis turns access certification from a broad checklist into a targeted review of what is unusual, stale, or out of step with peers in the same function. That matters because certification failures are often caused by review fatigue, not lack of policy. When reviewers see every entitlement as equally important, excessive access is easy to miss, especially in environments with many service accounts, shared roles, and inherited permissions.

The risk is even higher in identity-heavy environments where access sprawl is already the norm. NHI Mgmt Group notes that Ultimate Guide to NHIs reports that 97% of NHIs carry excessive privileges, which is a strong signal that outlier-based review is not optional. In practice, peer grouping helps reviewers focus on permissions that do not match job function, team norms, or historical usage. That makes certification more defensible and easier to scale across human and non-human identities. The same logic aligns with the OWASP Non-Human Identity Top 10, which treats privilege sprawl and weak visibility as core control failures. In practice, many security teams discover the most concerning access only after an audit exception or incident forces a manual review.

How It Works in Practice

Peer-group analysis works best when the certification tool compares each identity against a reference set built from role, team, application scope, geography, and job family. The point is not to make every peer identical. The point is to identify access that is materially different from the baseline and therefore deserves human attention. For access certification, that usually means highlighting outliers such as unused admin rights, unusual cross-system entitlements, or access inherited from prior assignments.

Operationally, security teams should start by defining clean peer groups and then mapping permissions, recent activity, and ownership metadata into the review. Current guidance suggests combining static entitlement data with behavioural context, because permissions alone can be misleading. A dormant account with privileged access may be more concerning than a heavily used standard account, and a low-activity service identity may still be critical if it can reach sensitive systems. NHI Mgmt Group’s Key Challenges and Risks section is useful here because it frames excessive access as a visibility and governance problem, not just a cleanup exercise.

• Group identities by job function, application tier, and business unit before review begins.
• Flag entitlements that exceed the peer median or fall outside the approved pattern for that role.
• Separate inherited access from explicit access so reviewers can see what can actually be removed.
• Use activity data to distinguish unused access from required but infrequent access.
• Escalate exceptions to control owners when the peer baseline is itself drifting.

Peer analysis is strongest when it is paired with lifecycle controls such as rotation, offboarding, and ownership validation, because certification alone does not remove risk. These controls tend to break down when role definitions are stale or when peer groups are too broad to represent a real operational baseline.

Common Variations and Edge Cases

Tighter peer-group analysis often increases review overhead, requiring organisations to balance precision against the effort needed to maintain high-quality reference groups. That tradeoff is especially visible in dynamic environments where project teams shift often, contractors cycle in and out, or the same identity is used across multiple systems. In those cases, a single peer group may hide risk rather than reveal it.

Best practice is evolving for edge cases such as privileged service accounts, API keys, and shared operational roles. For those identities, there is no universal standard for peer certification based on human-like job titles, because the access pattern is often system-driven rather than role-driven. Instead, reviewers should compare workload purpose, owner, scope, and rotation status. That approach fits the broader NHI governance lessons in 52 NHI Breaches Analysis, where weak visibility and excessive privilege repeatedly appear as root causes.

Peer grouping also has limits when the baseline itself is compromised. If an entire team has drifted into over-entitled access, the analysis may normalize bad practice unless control owners periodically reset the reference model. In those situations, peer analysis should be treated as a triage tool, not the final authority.

Related resources from NHI Mgmt Group

• How should teams use AI to improve access certification without weakening accountability?
• What breaks when access governance is not standardised across a hospital group?
• Who should approve access to sensitive data when certification enrichment is in place?
• Should organisations exclude birthright access from certification campaigns?